1. Technical Field
The present invention relates to a projection display system utilizing a reflection display device.
2. Background Art
There exists a projection display system utilizing a reflection display device such as a reflection liquid crystal display device or a micromirror display device, generally referred to as DMD (digital micromirror display), in which a plurality of pixels are arranged in a matrix, whereby reflected light that has entered from a front surface of the device is controlled by the plurality of pixels so arranged so as to project forward an image beam. The projection display system includes the reflection display device, a light source system optical member for projecting an illumination beam toward the reflection display device from a direction inclined in one direction relative to a front surface direction of the reflection display device and a projection system optical member for projecting the illumination beam projected from the reflection display device onto a projecting surface such as a screen.
In this projection display system, an illumination beam from the light source system optical member including a light source portion is caused to enter the reflection display device from the direction inclined in one direction relative to the front surface direction of the reflection display device. Due to this, the luminance of a displayed image that is displayed by the reflection display device needs to uniform over the whole area of a display area where the plurality of pixels are arranged in the matrix, and the illumination beam from the light source system optical member needs to be corrected into a parallel beam before it is incident on the reflection display device.
To make this happen, the applicant for this subject patent application has already proposed and disclosed, as a Japanese Unexamined Patent Publication No. 2003-149599, the aforesaid projection display system in which a relay lens is disposed on a front surface side of the reflection display device for correcting the illumination beam that has entered from a front surface of the lens which faces the light source system optical member and the projection system optical member into a parallel beam which follows a direction inclined at a predetermined angle relative to the front surface direction of the reflection display device so as to be incident on the reflection display device and allowing the image beam projected from the reflection display device to be incident on the projection system optical member. This projection display system is such that the parallel beam which is free from irregular luminance is emitted to the reflection display device so as to form an image by a reflection beam from the reflection display device, so that the image beam from the reflection display device is projected on the projection surface by the projection system optical member.